1. Field of the Invention
The present invention relates to: a dismounting method for a fastening member in which a fastening member is dismounted from a base material, wherein the fastening member includes a head and a body, the body is inserted into a fastening hole formed in the base material, and the head contacts a peripheral edge of the fastening hole when in a fastened state with the body; a dismounting device for a fastening member; an attachment construction of a fastening member; and a production system using the dismounting method for a fastening member.
2. Discussion of Background
Presently known techniques for uniting any one of a steel plate, plastic base materials to each other, or a member to a base material, include welding, bonding, mechanical fastening, etc.
Welding techniques are desirable for joining materials requiring a great uniting strength, but have the drawback that large-scaled, expensive equipment is usually necessary to accomplish the joining and thus, a large amount of space is required in order to perform the joining safely.
Bonding techniques can be carried out inexpensively and in a small space, as compared with the above-mentioned welding techniques, but have the drawback that the attitude of a base material has to be constantly maintained until the bonding agent is set and thus, a lot of time is required to accomplish the uniting.
Further, in both welding and bonding techniques, when the base materials are united and either, inferior uniting occurs so as to require re-uniting, or a base material is desired to be recycled and reused, it is very difficult to dismount the base materials from each other at the united portion without damaging the base materials.
On the other hand, presently know mechanical fastening techniques include screw fastening, pin fastening, and rivet fastening.
Presently known screw fastening techniques include, for example, the following two methods. In a first method, as illustrated in FIG. 92(a), a bolt 3 is the fastening member and is inserted into fastening holes 1a and 2a of base materials 1 and 2, respectively, and then a nut 4 is screwed onto the end of the bolt 3 using a spanner to thereby mechanically unite the base materials 1 and 2 to each other. In a second method, as illustrated in FIG. 92(b), a tapping screw 5 is the fastening member and is threadingly engaged with thread portions formed on the inner surface of fastening holes 1a and 2a in the base materials 1 and 2, respectively, via a screw driver to mechanically unite the base materials 1 and 2 to each other.
Presently known pin fastening techniques include, for example, the following two methods. In a first method, as illustrated in FIG. 93(a), a pin 6 is the fastening member and is inserted into fastening holes 1a and 2a of the base materials 1 and 2, respectively, and opposite ends of the pin 6 are caulked, using a caulking machine or a caulking tool, to thereby mechanically unite base materials 1 and 2 to each other. In a second method, as illustrated in FIG. 93(b), a shaft 7 is the fastening member and is inserted into a fastening hole of base material 1 and then, an end of the shaft 7 is caulked, using a caulking machine or a caulking tool, to thereby mechanically unite the base material 1 and the shaft 7 to each other.
Presently known rivet fastening techniques include, for example, the following two methods. In a first method, the fastening member is either a solid rivet 8, as illustrated in FIG. 94(a), or a tubular rivet 9, as illustrated in FIG. 94(b). Then, either the solid rivet 8 or the tubular rivet 9 is inserted into the fastening holes 1a and 2a of base materials 1 and 2, respectively, and then, the ends of either the solid rivet 8 or the tubular rivet 9 are crushed, as illustrated in FIG. 94(d) and FIG. 94(e), respectively, to thereby mechanically unite the base materials 1 and 2 to each other. In a second method, the fastening member is a blind rivet 10, as illustrated in FIG. 94(c), which is inserted into fastening holes 1a and 2a of base materials 1 and 2, respectively, and then, the end of the blind rivet 10 is crushed using a core shaft, which will be described below, to thereby mechanically unite the base materials 1 and 2 to each other, as shown in FIG. 94(f).
The blind rivet 10, as shown in FIG. 94(c), includes a rivet body 11 and a mandrel (core shaft) 12, wherein the mandrel 12 is inserted into an shaft hole 11a of the rivet body 11. For example, base materials 1 and 2 are mechanically fastened to each other in the following procedure.
In this rivet fastening technique, first, a body 11b of the blind rivet 11 is inserted into fastening holes 1a and 2a of the base materials 1 and 2, respectively, as shown in FIG. 95(a), and a blind rivet fastening device 13 is placed at an end of the mandrel 12, as shown in FIG. 95(b).
Then, as shown in FIG. 95(c), a nose piece 13a of the blind rivet fastening device 13 is brought into close contact with a head 11c of the rivet body 11, and the blind rivet fastening tool 13 is actuated, while the head 11c is pressed against the base material 1 via the nose piece 13a.
Thereby, the mandrel 12 is gripped by a jaw member 13b (i.e., a fastening shaft gripping portion of the blind rivet fastening device 13) and pulled in the direction opposite of the pressing direction. A portion of the rivet body 11b, which extends outwardly past the bottom of the base material 2, is plastically deformed and crushed, thus being caulked and pressed against the base material 2.
When in this condition, the jaw member 13b is further pulled in the direction opposite of the pressing direction, the mandrel 12 is ruptured at a diameter-reduced portion 12b, as shown in FIG. 95(d), and the base materials 1 and 2 are fastened to each other via the blind rivet 10.
The blind rivet 10, of FIGS. 95(a)-(d), is fastened by the pulling of the mandrel 12 in the direction opposite the pressing direction so that the base materials 1 and 2 are united without having to support the back sides thereof. This rivet fastening method is suitable for uniting base materials 1 and 2 so that a person's hands are not required to be placed near the back sides of the base materials 1 and 2 in order to unite them.
Note that a conventional mechanical fastening technique known as "burring caulking" is shown in FIG. 96, wherein a shaft 7 (i.e., a rivet body 11b) is formed integrally with one base material 1 and is caulked to a fastening hole 2a of the other base material 2 to mechanically unite the base materials 1 and 2.
The above-described mechanical fastening techniques are desirable because: (1) a large apparatus is not required, as compared with the above-described conventional welding techniques; (2) the fastening can be accomplished easily and safely, even in a narrow space; and (3) the base materials 1 and 2 can be united in a short amount of time, as compared with the above-described bonding techniques.
However, the bodies of the fastening members, such as the pins, rivets, burring caulking, etc., used in mechanical fastening techniques, are plastically deformed and fastened to the base material. This may lead to drawbacks when the fastening member is fastened to the base material and inadequate fastening occurs, because the base material in order to remove the fastening member from the base material to recycle the base material, the fastening member has to be destroyed, a significant amount of time must be expended to dismount the fastening member from the base material, and the base material is often damaged during the dismounting. That is, as the dismounting technique for a fastening member of this kind, a method as shown in FIG. 97 is generally known, and an example of the method will be explained with reference to the dismounting of the blind rivet 10 as the fastening member.
First, a head 11c of the blind rivet 10 is cut using a drill 14, and the head 11c of the blind rivet 10 is removed from a body 11b. Thereafter, the cut portion of the head 11c of the blind rivet 10 is separated from the body 11b and the body 11b slips out of the fastening holes 1a and 2a, so that the blind rivet 10 is pulled out of the base materials 1 and 2.
The above-mentioned dismounting method for a fastening member takes preparation time, such as for selection of a drill 14, and time for performing the cutting, etc. Further, as shown in FIG. 98, when the head 11c is cut using a drill 14, the extreme end of the drill 14 reaches the base material 1 so that the fastening hole 1a of the base material 1 is cut to make the fastening hole 1a larger that it originally was. Then, even if the base material 1 is recycled and re-fastened using the blind rivet 10, it is not possible to secure sufficient fastening force. Generally, if the base materials 1 and 2 are damaged when the dismounting work for a fastening member is carried out, it is difficult to recycle the base materials 1 and 2.
Further, in the case of the dismounting method for a fastening member using the drill 14 of this kind, there is a further problem in that when the head of the fastening member is cut, a free running phenomenon occurs in which the fastening member rotates integrally with the drill 14 as the drill 14 rotates and this may either scratch the base material 1 or fail to cut the head 11c. In particular, in the case where the base material 1 is used for the exterior of products, when the surface of the base material 1 is scratched, the quality of the product is materially lowered, and the base material 1, having such a scratch as described, cannot be reused or recycled. In other words, when the dismounting method uses a drill 14 for dismounting of the fastening member, the chances of the base material becoming of inferior quality, so as to not be recyclable, materially increases.
In view of the foregoing, in order to prevent the free running phenomenon of the fastening member as the drill 14 rotates, as shown in FIG. 97, the head 11c or the body 11b is gripped with a gripping tool 15, such as a plier or a pair of cutting pliers, so that the head 11c may be cut by the drill 14. However, this poses a problem in that, since a danger is involved if this work is carried out by one person, the work must be carried out by two or more persons, resulting in an increase of personnel expenses.
However, when the head 11c of the fastening member is plate-shaped so that it is difficult to grip the head 11c with a gripping tool 15, and when fastening is performed at portions of the base materials 1 and 2 where a person's hands cannot enter the back sides of the base materials 1 and 2, the body 11b cannot be gripped by the gripping tool 15, thus making it difficult to prevent the free running phenomenon from occurring.
In the case of the screw fastening, as shown in FIGS. 92(a) and 92(b), the fastening member, such as the bolt 3 and nut 4 or the tapping screw 52, can often be removed easily from the base materials 1 and 2. However, also in the case of the screw fastening, when either the engaging portion between the bolt 3 and the nut 4 becomes encrusted with rust and adhered, or when the engaging portion between the tapping screw 5 and the fastening holes 1a and 2a becomes adhered, the drawback may occur that the threads are broken and the fastening member, made up of the bolt 3 and nut 4 or the tapping screw 5, cannot be dismounted from to the base materials 1 and 2. Further, if a corner of the head of the bolt 3, a corner of the nut 4, and a head of the tapping screw 5 are damaged, a great difficulty ensues in removal of the bolt 3, the nut 4, and the tapping screw 5 from the base materials 1 and 2.